Thesis Opportunities

Master thesis:

Active timing drift compensation system for FLASHForward

Project description
FLASHForward is a new facility allowing experimental demonstration of novel electron injection techniques in plasma wakefield accelerators. One of these relies on an ultrashort, 30 fs laser pulse selectively ionising some electrons inside the wakefield driven by an electron beam with a duration of tens of femtoseconds. Thus, femtosecond-level synchronisation between the laser and electron beam is required. A synchronisation system between the short-pulse laser oscillator and electron beam source has already been implemented. However, temperature, humidity and other environmental factors will affect the more than 60 m long laser beam transport line and thus the arrival time of the pulses at the plasma interaction. This project will involve the design and implementation of an active timing drift compensation system, allowing the laser pulses to be kept accurately timed to the electron beam.

Kristjan Poder, DESY (FLA), tel.: 040 / 8998 - 2483
Jens Osterhoff, DESY (FLA), tel.: 040 / 8998 - 1854

Study of the impact of coherent-synchrotron radiation effects on a multi-stage PWFA collider

Project description
Beam-driven plasma-wakefield acceleration (PWFA) is a novel concept for particle acceleration. The accelerating fields in this scheme exceed those in conventional radio-frequency cavities by 2 to 3 orders of magnitude and, therefore, might enable next-generation colliders for particle physics and other high-energy accelerators in a much smaller footprint.

Reaching high energies in the TeV range in such a plasma-based collider is likely to require staging - employment of a sequence of  plasma modules, each providing a fixed energy gain in the GeV range. This requires injection and extraction of the electron beam into every plasma module, which implies electron beams moving on curved trajectories inside the corresponding dipole magnets.

It is known that coherent-synchrotron radiation affects high current  electron beams traveling on such curved trajectories, namely it increases the transverse emittance, perturbs the longitudinal phase space, and, most importantly, generates beam asymmetries (centroid offsets) leading to the so-called hosing instability in a plasma, which in turn prevents quality-preserving acceleration.

A theoretical study is required to evaluate the magnitude of this effect, assess the feasibility of a staged PWFA collider and to optimize the injection/extraction sections.

What you will learn
Fundamentals of conventional and plasma-based accelerator physics, practical accelerator design, numerical simulations for accelerators, etc.

Vladyslav Libov, Uni HH and DESY (FLA), tel.: 040 / 8998 - 5055
Jens Osterhoff, DESY (FLA), tel.: 040 / 8998 - 1854